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The present invention relates to cutting tools such as drills having a liquid as both a coolant and a lubricant supplied to the cutting face of the tool and the material being cut and, more particularly, to liquid flow path restrictions for such tools.
Tools that are used to cut through hard material operate in the presence of large amounts of heat generated thereby and undergo rapid wear of the tool cutting surface in the absence of measures to reduce same. One such measure is to provide a liquid serving as both a coolant and a lubricant at the tool cutting surface where it engages the material being cut. In one such situation, in which a drill is being used to form a hole in a hard material, such a drill can be provided with an interior fluid flow channel to allow transport therethrough of such a liquid under substantial pressure to the interface between the drill and the material thereby allowing that liquid to serve as both a coolant and a lubricant for the drill cutting surface. Such a liquid brought to the drill cutting surface in addition aids in forcing out cut away portions of the material being cut as well as aiding in preventing the drill bit from overheating which can lead to increased tool wear or even breakage.
In such a cutting situation, the liquid pressure may have to be quite large for the liquid to be effective at the tool cutting surface where it meets the material being cut. Liquid pressures from a few hundred pounds per square inch to thousands of pounds per square inch may be needed depending on the particular situation. Fluid confinement in the toolholder at appropriate locations and in the interior fluid flow channel of the tool except at the orifices of that channel where the liquid exits onto the tool cutting surface is necessary if such liquid pressures are to be maintained during operation of the tool. Thus, the pressurized liquid must be confined to flowing with respect to the tool only through the transfer channel and out the orifices thereof in the cutting tool surface, and not along other circumventing paths. That is, the liquid from the pressurized reservoir thereof in the toolholder must flow through the transport channel in the drill and not through other parallel paths to the atmosphere.
One such parallel path for the liquid are leakage paths around the shaft of a drill bit being used as the operating tool. Such leakage has been limited in the past by providing some sort of a seal around the periphery of the drill bit so that fluid reaching the drill shaft from the pressurized reservoir is prevented, at least in large part, from flowing along the sides of the drill. One such seal is shown in U.S. Pat. No. 5,567,093 to the present inventor based on a rigid seal positioned at one end about the drill with an O-ring therebetween, and with the opposite end of the rigid seal being captured between the collet chuck and the collet nut so as to be held by the tightened nut against the collet chuck and the liquid pressure. However, changes in shapes of collets and collet nuts that have previously been commonly used, and increases in liquid pressures being used, can limit the suitability of such a rigid seal. Thus, there is a need for a tool shaft seal system in connection with a toolholder that accommodates various collet chuck shapes and higher liquid pressures for liquids used as a coolant and lubricant at the cutting surface of the tool during operation thereof in cutting materials.
The present invention provides a seal assembly for a toolholder with a collet clamping member about an extended tool placement opening that can be forced radially inward to clamp a tool having a forcing ring in which at least in part the clamping member can be positioned with a seal ring opening positioned adjacent to, and coaxially with, the clamping member with this opening having an inner surface supporting an engager accommodation such as threading. A seal ring with a tool insertion opening including a surrounding O-ring holder has an outer surface supporting an engager, such as threading, that can be removably engaged with the forcing ring engager accommodation in the forcing ring seal ring opening to place this seal ring in a selected position therein. An O-ring is provided in the seal ring O-ring holder. The seal ring has a pair of ends with one of these ends having a pair of holes therein opposite one another across the tool insertion opening.